This invention relates generally to functional electrical stimulation systems and more particularly to techniques to produce stimulation patterns for functional electrical stimulation systems usable for lower and/or upper extremities.
As is known in the art, research in upper and lower extremity functional electrical systems has been ongoing for a number of years. Functional electrical stimulation uses an electronic system to generate electrical pulses that are delivered to muscles o a patient who has muscle movement impairment. The muscle movement impairment is due to some condition that causes muscle paralysis. This condition can be nerve damage c used by accident or disease. The functional electrical stimulation system produces electrical signals that can be used by the patient to control muscle movement.
Practical electrical stimulation systems require a stimulation system that is small, lightweight and portable. Such a system would to allow a subject patient to operate the system to learn to perform everyday activities. On the other hand a practical system requires sufficient versatility and power to enable practical utilization of generated electrical stimulation patterns to produce a variety of muscle movements.
Several portable systems have been described in the literature. As is known, one of the problems common to these systems is the approach used to generate the electrical signal patterns. The described systems are either built for upper or lower extremity movement but not both or either. In general, the known systems cannot handle different types of sensors. Thus, systems are designed for a particular type of sensor associated with the desired type of stimulation. Further, the approaches used to process inputs to produce stimulation waveform generally are not sufficiently robust to accommodate different sensors.
Different sensors and algorithms are necessary for each type of stimulation because the characteristics of the upper and lower extremity movements are different. Lower extremity movements can be characterized as repetitive, predictable movements, whereas upper extremity movements are more spontaneous in character. A second problem is that for practical, useful movements of muscles generally several muscles must be operates in unison or concert to produce the practical movement. Thus, in addition to providing an algorithm which allows for relatively easy generation of such produced muscle movements, it is also desirable to provide an overall system that can be adapted for upper or lower extremity stimulation or both.
In accordance with the present invention, a memory containing a data file having da a that under control of a program executed by a function al electrical stimulator (FES) system produces at least one functional electrical stimulation pattern. The pattern under control of the program provides signals that ire coupled to electrodes used by the functional electric al stimulator. The data file includes a table storing control and pattern generation information and separately storing electrode activation data for each electrode used by the portable stimulator. With such an arrangement, by storing characterization data separately from pattern data, it allows the Stimulation Pattern to be unaffected by a change in electrode characteristics, since to compensate only requires a change in the parameters of the electrode. It also allows generalized Pattern templates to be produced with most of the user specific information generated directly from Profiling sessions with a patient. This provides a unified approach to producing electrical signal patterns which takes into consideration the various complexities involved in controlling muscles.
In accordance with a further aspect of the present invention, a method of generating stimulation patterns for execution by a functional electrical stimulator system includes the steps of forming a plurality of primitive movement patterns by electrical y stimulating selected electrodes contacting a subject patient and choosing for each one of said plurality of primitive movement patterns one or more of said selected electrodes to produce the primitive movement. The method combines from the plurality of primitive movements at least one or more of the primitive movements to produce an interval pattern for each one of a plurality of desired interval movement and combines at least one or more of said interval movements to form a complex movement controllable by a user. With such an arrangement, a hierarchical approach to forming complex movements is provided. This insulates the Stimulation Pattern from the specifics of the individual electrodes profiling information and location. Thus all patterns are generated through combining of primitive movements, which are logical mappings of a desired effect (movement) to the physical stimulation required to obtain that effect, as determined during electrode profiling sessions. This allows the pattern to be unaffected by a change in electrode characteristics, since to compensate requires only a change in the parameters of the primitive movements. It also allows generalized Pattern templates to be produced with most of the user specific information generated directly from the Profiling session.